1. Field of the Invention
The present invention relates to a teleconference system which exchanges speech, video etc. through a communication circuit in real time.
2. Description of the Prior Art
Heretofore, a video telephone system and a teleconference system have been known as systems in each of which speech, video etc. are exchanged through a communication circuit in real time.
The video telephone system is chiefly intended for telephonic communications between one person and another similar to a conventional telephone. On the other hand, the teleconference system is intended for teleconference between a number of people, and it has a construction in which importance is attached to meeting functions required for such a teleconference.
A prior-art equipment for the teleconference system is constructed by combining independent devices such as a display unit, a codec, a microphone and a console. In some cases, a document camera, an electronic blackboard and a small-sized computer are further combined in accordance with functions required for conferences.
There is also a teleconference equipment wherein fundamental devices are housed in a single rack so as to be movable, thereby dispensing with the need for an exclusive conference room.
Techniques relevant to these equipments are disclosed in the official gazettes of Japanese Patent Applications Laid-open No. 39790/1990 and No. 22989/1990.
In addition, Japanese Patent Applications relevant to teleconference systems filed by the assignee of the present application are Patent Applications Laid-open Nos. 166884/1991 and 120889/1992, and Patent Applications Nos. 406984/1990, 25987/1991, 25991/1991, 34009/1991, 174025/1991, 174031/1991 and 174049/1991.
Most of the video telephone systems in the prior art do not have the high-degree functions necessary for teleconferences such as the teleconference systems have, because it is presumed that they are only used between one person and another. On the contrary, teleconference systems in the prior art are inherently endowed with such high-degree functions. In consequence, however, they become high in cost and large in size and are not suitable for a simple telephone conversation between one person and another.
In general, it is required of a teleconference that many people can watch a screen at the same time. Therefore, a display unit should desirably be large to some extent. Besides, codecs for processing a large amount of picture information at high speed have not to date been reduced in size considerably, and most of them are large in size.
For these reasons, the prior-art equipment for the teleconference system constructed by combining such devices is large in scale, and a teleconference room for exclusive use is usually necessitated. Accordingly, the introduction of a teleconference system involves a heavy financial burden. Moreover, when holding the teleconference, conferees must move to the teleconference room which is inconvenient. In this regard, even portable teleconference equipment needs many people to move it on account of its size and weight and cannot be used with ease.
Meanwhile, the display unit which is most common at present is a CRT display device, which is mainly used for displaying the received pictures of television broadcasting. Since such a display unit is essentially a versatile device, it can construct a BS (broadcasting by satellite) receiving system conjointly with a BS receiver module connected thereto and a playback display system for recorded pictures conjointly with a video tape recorder module connected thereto. Therefore, such display units are already installed in many places where people gather, such as living rooms in homes and conference rooms. Herein, the display unit for use in the teleconference system need not be a special device. Incidentally, this is also true of the video telephone system wherein speech and pictures are exchanged in one to one correspondence.